I have the M&P 9c and FS 40 and never a problem with either. However, I also have an S&W sigma 40 and had bad failure to feed issues. Two or three rounds from every magazine of fmj rounds would hang on the feed ramp and it would not feed hollow points at all. I sent it back to S&W and they cut a small champer in the leading edge of feed ramp and another where the feed ramp joined the chamber.

After that it would feed anything and never had another problem. I even bought some of the really cheap steel case ammo and it worked with no problem.